This invention relates to use of OO-t-amyl-O(2-ethylhexyl)monoperoxy-carbonate as a curing catalyst for bulk molding compounds (xe2x80x9cBMCxe2x80x9ds) and sheet molding compounds (xe2x80x9cSMCxe2x80x9ds). BMCs and SMCs find extensive use in the production of parts for autos, trucks, buses, other transportation, electrical and electronic applications. For cars and trucks, for example, several hundred million pounds of SMC annually go into the production of body panels and several million pounds of BMC annually go into the production of head lamp housing.
Organic peroxides having a ten hour half-life temperature of about 97-104xc2x0 C., such as t-butyl perbenzoate with a ten hour half-life temperature of 104xc2x0 C., have been used as the catalysts to cure these SMCs and BMCs. Patents describing these molding compounds and the processes for preparing same include U.S. Pat. Nos. 4,535,110 and 4,622,354 (for SMCs), and U.S. Pat. No. 4,451,610 (for BMCs), the specifications of which are incorporated herein by reference. The problem has been that the typical organic peroxide, if it has a fast cure time, also has a fast gel time, in which case the part cannot be properly molded at a fast molding cycle since the SMC or BMC does not have enough time to fill the mold at high temperature. Thus, what is desired is a peroxide with a high ratio of gel time to cure time so that the SMC or BMC will not gel up too quickly for the mold to be filled properly, yet cure quickly so that the parts can be produced quickly.
Use of OO-t-amyl-O(2-ethylhexyl)monoperoxycarbonate as a curing catalyst for bulk molding compounds (xe2x80x9cBMCxe2x80x9ds) and sheet molding compounds (xe2x80x9cSMCxe2x80x9ds) is provided.